1. Field
The present disclosure relates to a method of manufacturing an electronic device and, more particularly, to a method of manufacturing a three dimensional (3D) semiconductor device.
2. Description of the Related Art
A non-volatile memory device is a memory device in which stored data is maintained even when the power supply to the device is turned off. Recently, improvement of the degree of integration of two-dimensional (2D) memory devices, in which memory cells are formed in a single layer on a silicon substrate, has reached a limit. For further enhancing the degree of integration of memory devices, a three dimensional (3D) non-volatile memory device, in which a plurality of memory cells are vertically stacked on a silicon substrate, has been suggested.
A 3D non-volatile memory device typically includes a plurality of interlayer insulating layers and word lines which are alternately stacked. Channel layers pass through the interlayer insulating layer and the word lines, and memory cells are stacked along the channel layers. Patterning the word lines in a step form has been proposed for some time, wherein contact plugs and metal wires are formed to connect to the word lines so that each of the word lines may be readily controlled.
However, heretofore, it has been highly difficult to pattern the word lines in a step form. Also, a step structure occupies a large area, so it places a limit in improving the integration density of 3D memory devices.